ABSTRACT
The purpose of this study was to evaluate the antimicrobial properties of a new formulation containing silver nanoparticles, named Nano Silver Fluoride (NSF), to inhibit Streptococcus mutans biofilm formation on children's dental enamel. The variations in dental biofilm pH and in the Simplified-Oral-Hygiene-Index (OHI-S) also were evaluated after the treatment with NSF. This was a randomized, double-blind, crossover and prospective pilot clinical trial study in which 12 schoolchildren, aged between 7-8 years, had their dental enamel treated with two solutions: S1 - Nano Silver Fluoride and S2 - negative control (saline solution), in different experimental moments. The dental biofilm adhered to enamel treated with NSF had lower values of S. mutans viability (absorbance) and colony forming units (CFU) than the S0 (baseline) and S2. There was a statistically significant difference between the OHI-S mean values of S0 and S1. There were no differences between the biofilm pH (both before and after the use of the test substances) and among the different groups. These properties suggest that NSF has bactericidal effect against S. mutans biofilm and it may be used for clinical control and prevention of dental biofilm formation.
Subject(s)
Biofilms , Metal Nanoparticles , Silver/chemistry , Streptococcus mutans/drug effects , Child , Colony Count, Microbial , Cross-Over Studies , Double-Blind Method , Female , Humans , Hydrogen-Ion Concentration , Male , Metal Nanoparticles/chemistry , Oral Hygiene Index , Pilot Projects , Prospective Studies , Streptococcus mutans/physiologyABSTRACT
Cherry tomato (Lycopersicon esculentum Mill) fruits are susceptible to contamination by Aspergillus flavus, which may cause the development of fruit rot and significant postharvest losses. Currently there are significant drawbacks for the use of synthetic fungicides to control pathogenic fungi in tomato fruits, and it has increased the interest in exploring new alternatives to control the occurrence of fungal infections in these fruits. This study evaluated the efficacy of chitosan (CHI) from Mucor circinelloides in combination with carvacrol (CAR) in inhibiting A. flavus in laboratory media and as a coating on cherry tomato fruits (25°C, 12 days and 12°C, 24 days). During a period of storage, the effect of coatings composed of CHI and CAR on autochthonous microflora, as well as on some quality characteristics of the fruits such as weight loss, color, firmness, soluble solids, and titratable acidity was evaluated. CHI and CAR displayed MIC valuesof 7.5 mg/mL and 10 µL/mL, respectively, against A. flavus. The combined application of CHI (7.5 or 3.75 mg/mL) and CAR (5 or 2.5 µL/mL) strongly inhibited the mycelial growth and spore germination of A. flavus. The coating composed of CHI (3.75 mg/mL) and CAR (2.5 or 1.25 µL/mL) inhibited the growth of A. flavus in artificially contaminated fruits, as well as the native fungal microflora of the fruits stored at room or low temperature. The application of the tested coatings preserved the quality of cherry tomato fruits as measured by some physicochemical attributes. From this, composite coatings containing CHI and CAR offer a promising alternative to control postharvest infection caused by A. flavus or native fungal microflora in fresh cherry tomato fruits without negatively affecting their quality over storage.
ABSTRACT
This study aimed to evaluate the cytotoxicity and bactericidal properties of four silver nanoparticle (AgNP) colloids and their ability to inhibit Streptococcus mutans biofilm formation on dental enamel. The cytotoxicity of AgNPs was evaluated based on signs of vascular change on the chorioallantoic membrane using the hen's egg test (HET-CAM). Bactericidal properties and inhibition of S. mutans biofilm formation were determined using a parallel-flow cell system and a dichromatic fluorescent stain. The percentage of viable cells was calculated from regression data generated from a viability standard. AgNP colloids proved to be non-irritating, as they were unable to promote vasoconstriction, haemorrhage or coagulation. AgNP colloids inhibited S. mutans biofilm formation on dental enamel, and cell viability measured by fluorescence was 0% for samples S1, S2, S3 and S4 and 36.5% for the positive control (diluted 30% silver diamine fluoride). AgNPs are new products with a low production cost because they have a lower concentration of silver, with low toxicity and an effective bactericidal effect against a cariogenic oral bacterium. Moreover, they do not promote colour change in dental enamel, which is an aesthetic advantage compared with traditional silver products.
Subject(s)
Biofilms/drug effects , Metal Nanoparticles , Silver/chemistry , Streptococcus mutans/drug effects , Animals , Anti-Bacterial Agents/pharmacology , Chickens , Female , Metal Nanoparticles/chemistryABSTRACT
Microbiological processes were used for chitin and chitosan production by Mucor circinelloides (UCP 050) grown in yam bean (Pachyrhizus erosus L. Urban) medium. The polysaccharides were extracted by alkali-acid treatment and structural investigations by X-ray diffraction, Fourier transform IR analysis, viscosity and thermal analysis by TG, DTG, and DTA were done. The highest biomass yield (20.7 g/L) was obtained at 96 hours. The highest levels of chitosan (64 mg/g) and chitin (500 mg/g) were produced at 48 and 72 hours, respectively. It was demonstrated that yam bean shows great potential as an economic medium and it is possible to achieve a good yield of chitosan with chemical properties that enable its use in biotechnological applications.
Subject(s)
Chitin/metabolism , Chitosan/metabolism , Culture Media/chemistry , Mucor/metabolism , Pachyrhizus/chemistry , Acetylation , Batch Cell Culture Techniques , Calorimetry, Differential Scanning , Chitin/chemistry , Chitosan/chemistry , Fermentation , Powder Diffraction , X-Ray DiffractionABSTRACT
Listeria monocytogenes is widely distributed in nature and the infection listeriosis is recognized as a potential threat for human health because of its mortality rate. The objective of this study was to evaluate the growth profile and chitosan production by Mucor rouxxi UCP 064 grown in yam bean (Pachyrhizus erosus L. Urban) medium. It was also to assess the anti-L. monocytogenes efficacy of the obtained chitosan. Higher values of biomass of M. rouxxi (16.9 g.L¹) and best yield of chitosan (62 mg.g-1) were found after 48 h of cultivation. Residual glucose and nitrogen in the growth media were 4.1 and 0.02 g.L¹ after 96 h, respectively. Obtained chitosan presented 85 percent of degree of deacetylation and 2.60 x 10(4) g.mol-1of viscosimetric molecular weight. Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) values of chitosan against L. monocytogenes ATCC 7644 were, respectively, 2.5 and 5.0 mg.mL-1. At 2.5 and 5.0 mg.mL-1 chitosan caused cidal effect in a maximum time of 4 h. Bacterial count below 2 log cfu.mL-1were found from 2 h onwards and no recovery in bacterial growth was noted in the remainder period. These results show the biotechnological potential of yam bean medium for chitosan production by Mucor rouxxi and support the possible rational use of chitosan from fungi as natural antimicrobial to control L. monocytogenes.
Listeria monocytogenes apresentase como um microrganismo amplamente distribuído na natureza, sendo que a infecção listeriose é reconhecida como uma potencial ameaça a saúde humana devido a sua taxa de mortalidade. O objetivo deste estudo foi avaliar o perfil de crescimento e de produção de quitosana por Mucor rouxxi UCP 064 cultivado em meio jacatupé (Pachyrhizus erosus L. Urban), bem como avaliar a eficácia anti-L. monocytogenes da quitosana produzida com vistas a uma possível aplicação em alimentos. Os mais elevados valores de biomassa de M. rouxxi (16,9 g.L¹) e o maior rendimento na produção de quitosana (62 mg.g-1) foram encontrados após 48 horas de cultivo. As quantidades residuais de glicose e nitrogênio no meio de crescimento após 96 horas foram 4,1 e 0,02 g.L¹ , respectivamente. A quitosana obtida apresentou grau de deacetilação de 85 por cento e peso molecular de 2,6 x 10(4) g.mol-1. Os valores da Concentração Inibitória Mínima (CIM) e Concentração Bactericida Mínima (CBM) da quitosana sobre L. monocytogenes ATCC 7664 foram, respectivamente, 2,5 e 5,0 mg.mL-1. Nas concentrações de 2,5 e 5,0 mg.mL-1a quitosana fúngica causou um efeito bactericida em um tempo máximo de 4 horas. Valores de contagens menores que 2 log ufc.mL-1foram encontrados a partir de 2 horas, sendo que nenhuma recuperação no crescimento bacteriano foi encontrado até 96 horas. Estes resultados mostram o potencial biotecnológico do meio jacatupé para produção de quitosana por Mucor rouxxi, bem como suportam o possível uso racional de quitosana fúngica como antimicrobiano natural para controlar o crescimento de L. monocytogenes.
ABSTRACT
Listeria monocytogenes is widely distributed in nature and the infection listeriosis is recognized as a potential threat for human health because of its mortality rate. The objective of this study was to evaluate the growth profile and chitosan production by Mucor rouxxi UCP 064 grown in yam bean (Pachyrhizus erosus L. Urban) medium. It was also to assess the anti-L. monocytogenes efficacy of the obtained chitosan. Higher values of biomass of M. rouxxi (16.9 g.L(-1)) and best yield of chitosan (62 mg.g(-1)) were found after 48 h of cultivation. Residual glucose and nitrogen in the growth media were 4.1 and 0.02 g.L(-1) after 96 h, respectively. Obtained chitosan presented 85 % of degree of deacetylation and 2.60 x 10(4) g.mol(-1) of viscosimetric molecular weight. Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) values of chitosan against L. monocytogenes ATCC 7644 were, respectively, 2.5 and 5.0 mg.mL(-1). At 2.5 and 5.0 mg.mL(-1) chitosan caused cidal effect in a maximum time of 4 h. Bacterial count below 2 log cfu.mL(-1) were found from 2 h onwards and no recovery in bacterial growth was noted in the remainder period. These results show the biotechnological potential of yam bean medium for chitosan production by Mucor rouxxi and support the possible rational use of chitosan from fungi as natural antimicrobial to control L. monocytogenes.
ABSTRACT
No Setor de Odontologia do Ambulatório da Mulher do Instituto Materno Infantil de Pernambuco - IMIP foram aplicados questionários a 40 gestantes, para avaliar o seu conhecimento em relação à sua saúde bucal e do seu futuro bebê, e o risco à doença cárie, pela presença de Streptococcus mutans. Foram analisadas informações quanto ao tipo de dieta, frequência e horário de higiene oral, e orientações recebidas quanto à saúde bucal. A presença de Streptococcus mutans foi avaliada por raspagem das faces vestibulares, linguais e interproximais dos incisivos e primeiros molares superiores e inferiores. O material coletado foi inoculado em meio Mitus Salivarius Bacitracin - MSB por 72 horas a 37ºC. As colônias de Streptococcus mutans foram identificadas através das características morfológicas e pela fermentação do manitol e sorbitol. Constatou-se que a maioria da população tem alto risco à doença cárie. O tipo de dieta e o risco à cárie, não apresentaram diferença significativa. A frequência e o horário das escovações foram importantes no controle da flora bacteriana bucal. A maioria das gestantes não tem conhecimento quanto ao problema da doença cárie, pois não sabem definir o que é a doença cárie, qual sua forma de transmissão, e quais os cuidados com a sua saúde oral e do seu bebê
